%\usepackage{tikz}
%\usetikzlibrary{trees}

%\pagestyle{empty}

\begin{figure}
% Set the overall layout of the tree
\tikzstyle{level 1}=[level distance=3.5cm, sibling distance=3.5cm]
\tikzstyle{level 2}=[level distance=3.5cm, sibling distance=2cm]

% Define styles for bags and leafs
\tikzstyle{bag} = [text width=4em, text centered]
\tikzstyle{end} = [circle,minimum width=3pt,fill, inner sep=0pt]

% The sloped option gives rotated edge labels. Personally
% I find sloped labels a bit difficult to read. Remove the sloped options
% to get horizontal labels. 
\begin{tikzpicture}[grow=right]
\node[bag] {$\Omega$}
    child {
        node[bag] {$(C,\cdot)$}        
            child {
                node[end, label=right:
                    {$(C,C) \rightarrow \frac{1}{4}=\frac{1}{2}\cdot\frac{1}{2}$}] {}
                edge from parent
                node[above] {$C$}
                node[below]  {$\frac{1}{2}$}
            }
            child {
                node[end, label=right:
                    {$(C,K) \rightarrow \frac{1}{4}=\frac{1}{2}\cdot\frac{1}{2}$}] {}
                edge from parent
                node[above] {$K$}
                node[below]  {$\frac{1}{2}$}
            }
            edge from parent 
            node[above] {$C$}
            node[below]  {$\frac{1}{2}$}
    }
    child {
        node[bag] {$(K,\cdot)$}        
        child {
                node[end, label=right:
                    {$(K,K) \rightarrow \frac{1}{4}=\frac{1}{2}\cdot\frac{1}{2}$}] {}
                edge from parent
                node[above] {$K$}
                node[below]  {$\frac{1}{2}$}
            }
            child {
                node[end, label=right:
                    {$(K,C)\rightarrow \frac{1}{4}=\frac{1}{2}\cdot\frac{1}{2}$}] {}
                edge from parent
                node[above] {$C$}
                node[below]  {$\frac{1}{2}$}
            }
        edge from parent         
            node[above] {$K$}
            node[below]  {$\frac{1}{2}$}
    };
\end{tikzpicture}
\label{diag:moedas_honestas}
\caption{Arvore descrevendo o lan\c{c}amento de 2 moedas honestas.}
\end{figure}